Disable Junk Mail Box Forwarding For Genuine Mails

Dear Sir

We are using Zimbra open source edition (zcs-8.0.2_GA_5569.UBUNTU12_64.20121210115059) with Ubuntu 12.04 server platform. currently we have some issue when user sending mails from the web mail to internal member, it will forward to recipient JUNK folder of the web mail without forwarding to INBOX.

Kindly please let me know without disabling AS/AV services from the zimbra, how we can overcome this critical issue.